The purpose of this article is to provide researchers and clinicians with a basic understanding of randomized clinical trials and to discuss their potential application to and limitations in the field of physical medicine and rehabilitation. A brief history of the development of randomized clinical trials, definitions of clinical trials, types of trials, and overview of methodological issues related to design are offered. Information is provided about the need to establish clear and concise study objectives and to explicitly define interventions and expected outcomes. Recommendations for developing clinical protocols and determining adequate sample size are presented, and various statistical considerations, including power, are discussed. Issues related to sampling strategies, and recruitment are reviewed. Importance of randomization and blinding is emphasized. Readers are also referred to other resources available on this topic. Finally, the authors describe shortfalls associated with the use of this design in rehabilitation research. These are further explored and discussed in terms of the actual benefits and limitations of randomized clinical trials in physical medicine and rehabilitation research. Recommendations are made regarding the use of this methodology to address relevant needs in clinical practice.